This invention relates to chewing gum. More particularly, it relates to a chewing gum which contains gum base, xylitol and flavor, but is free of added moisture and hygroscopic ingredients; and which is environmentally stable, i.e., which does not absorb significant amounts of water from the atmosphere to soften with age or give off significant amounts of water to the atmosphere to harden or stiffen with age.
Hammond et al., in U.S. Pat. No. 3,899,593, issued Aug. 12, 1975. disclose a chewing gum composition containing a major amount of xylitol. The composition of U.S. Pat. No. 3,899,593 requires from about 2 to about 6% by weight of glycerol, a hygroscopic material, "in order to soften the gum base to the extent that the base will be capable of binding the crystalline material." (col. 1, lines 64-65 and col. 2, lines 19-21).
Reggio et al., in U.S. Pat. No. 4,065,578, issued Dec. 27, 1977, disclose a chewing gum composition wherein xylitol is used as a major bulking sweetening agent, and a hydrocolloid is used as a binder between the gum base and xylitol. The hydrocolloid also serves as a humectant to hold moisture in the gum (col. 1, lines 27-32). Both U.S. Pat. Nos. 3,899,593 and 4,065,578 teach that a binder is necessary to produce a gum product with xylitol as the major bulking agent.
Klose et al., in U.S. Pat. No. 4,000,320, issued Dec. 28, 1976, and reissued Jan. 22, 1980 as U.S. Pat. No. Re. 30,197, disclose a chewing gum composition containing less than 50% xylitol; and, as stated in the Examples and in the Reissue Patent at col. 1, line 68 - col. 2, line 2, preferably less than 10% by weight, especially from 1 to 3.2% by weight. Klose et al. use xylitol to extend the storage stability of the gum, by enabling the gum to retain more moisture when the gum is stored at low relative humidities (col. 2, lines 51-57; reissue at col. 2, lines 64-67).
Bohni, in U.S. Pat. No. 3,914,434, issued Oct. 21, 1975, discloses the use of xylitol as a non-cariogenic sugar substitute.
Fronczkowski et al., in U.S. Pat. No. 4,127,677, issued Nov. 28, 1978, disclose a xylitol-coated chewing gum, made by applying a coating syrup of 55-70 percent solids, of which solids 95-99.5 percent is xylitol.
Patel et al., in U.S. patent application Ser. No. 159,870 filed Feb. 24, 1988, disclose a chewing gum which employs xylitol as a rolling compound.